Jesse Tyler Ferguson may star as one half of a gay couple raising a child on ABC's popular Modern Family but the openly gay actor has discovered that even fans of his and of the show are anti-gay marriage.

'The majority of my fans have been amazing and supportive,' the actor wrote on his Facebook page late Sunday (4 November). 'But I am in shock and ashamed of many of my 'fans' who are standing firm in their stance that I am 'less than' them because of my sexual orientation.'

Ferguson, engaged to marry Justin Mikita, has been speaking out in support of marriage equality as four US states - Washington, Maine, Maryland and Minnesota - prepare to vote on initiatives Tuesday (6 November).

Some of the feedback he has been getting has been disturbing.

'As an actor I have learned that I have to develop a thick skin but as a HUMAN I am having a harder time,' he wrote on Facebook. 'The amount of vitriol I have received in the past few days over my stance on marriage equality could kill an adult horse!'

With Facebook friends like these, he wonders who needs enemies.

Ferguson has invited 'friends' who do not support marriage equality to defriend him on Facebook.